Shaft seal device

ABSTRACT

A shaft seal device is provided in which movement of the seal lip is prevented and the sealing function can be reliably maintained by shaping the adapter so that the adapter is more readily pressed into and less liable to be dislodged from the cartridge, and by increasing the width in the radial direction. An external peripheral-side flange of the adapter fitted into the cartridge on the sealing fluid side of the first lip seal member is formed in a small-diameter tapered shape toward the web side, and the web is composed of an external-periphery-side portion having an orthogonal planar shape that is orthogonal to the center of the shaft, and a tapered internal-periphery-side portion that slopes to the sealing fluid side.

TECHNICAL FIELD

The present invention relates to a shaft seal device for sealing a spacebetween a housing and a rotating shaft, and particularly relates to alip seal-type shaft seal device for sealing the space between therotating shaft and the housing of an automotive water pump, a water pumpfor a home electric appliance, a light-load commercial-grade water pump,or the like.

BACKGROUND ART

The shaft seal device shown in FIG. 6 is a known as a conventional lipseal-type shaft seal device (hereinafter referred to as “prior art;”e.g., see Patent Document 1).

The shaft seal device of the prior art has a cartridge 62 fitted intothe internal periphery of a shaft hole 61 of a housing 60; a first seallip 63 made of rubber material fitted onto the cartridge 62 in anon-bonded state; a case 64 fitted onto the first seal lip 63 in anon-bonded state; a second seal lip 65 made of resin material crimpedonto and held by the case 64 and a backup ring 66 for supporting thesecond seal lip; and an adapter 67 fitted onto the cartridge 62 on asealing fluid side L of the first seal lip 63.

The adapter 67 in the shaft seal device of the prior art has across-sectional shape that is substantially the shape of the letter “c,”and has a cylindrical external peripheral flange 68 that is formedparallel to the axial center, as shown in FIG. 6. The adapter 67 cannotbe fitted into the cartridge 62 when the diameter of the externalperipheral flange 68 is excessively greater than the inside diameter ofa cylindrical part 69 of the cartridge 62, and conversely, the adapterreadily dislodges from the cartridge when the inside diameter isexcessively small. Therefore, the adapter 67 must be manufactured withrigorous dimensional precision.

There are cases in which the housing 60 is not modified and only thediameter of a shaft 70 is modified to, e.g., 12 mm to 8 mm. In such acase, the inside diameter dimension of the first seal lip 63, the case64, the second seal lip 65, the backup ring 66, and other members mustbe reduced in correspondence to the diameter of the shaft 70, and thewidth of the first seal lip 63 and the like in the radial direction isincreased. There is accordingly a problem in that when the adapter 67shown in FIG. 6 is used in an unmodified manner, the portion pressed bythe adapter 67 on a sealing fluid side L of the first seal lip 63 isnarrowed, and when the assembly is set on the shaft 70, the first seallip 63 moves in the shaft insertion direction and a gap is formedbetween the first seal lip 63 and the case 64. When an attempt is madeto reduce the inside diameter dimension of the adapter 67 and toincrease the width in the radial direction in order to adapt to such aproblem, the first seal lip 63 is compressed by the adapter 67 to theatmosphere side A because the internal peripheral side of the adapter isattached so as to slightly slope to the atmosphere side when the adapter67 is press-fitted to the cartridge 62, and there is a problem in thatthe inside diameter dimension of the first seal lip 63 changes and theseal function is negatively affected. Accordingly, the inside diameterdimension of the adapter 67 cannot be reduced to increase the width inthe radial direction.

FIGS. 5( a) and 5(b) show experimental results for the case in which theadapter 67 of the prior art shown in FIG. 6 is used in a shaft sealdevice having a small shaft diameter. It is apparent that the width ofthe adapter 67 in the radial direction is small, the lip part of thefirst seal lip 63 is pulled by the shaft 70 to the sealing fluid side L,a gap 69 is formed between the first seal lip 63 and the case 64, andthe first seal lip 63 is moved by assembly onto the shaft 70 when theadapter is assembled onto the shaft 70 of FIG. 5( a). On the other hand,FIG. 5( b) shows a state in which assembly has been completed and systempressure is applied to the sealing fluid side L, and it is apparent thatthe first seal lip 63 and the case 64 are brought into contact with eachother due to the pressure, and the first seal lip 63 is moved by thesystem pressure in the direction of the atmosphere side A.

In this manner, in the shaft seal device of the prior art, the seal lipreadily moves under the effect of assembly onto the shaft 70 and systempressure, and this becomes a cause of reduced sealing performance.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: WO 2010/061670 Pamphlet

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention was devised in order to solve the problems ofprior art described above, and an object thereof is to provide a shaftseal device that can prevent movement of the seal lip and reliablymaintain sealing function by making the shape of the adapter, firstly,to be more readily pressed into and less liable to dislodge from thecartridge, and secondly, to have a greater diameter in the radialdirection without a negatively effect on the sealing function.

Means for Solving the Problems

In order to achieve the objects described above, the shaft seal deviceof a first aspect of the present invention is a shaft seal device forsealing a space between a housing and a rotating shaft, the shaft sealdevice characterized in comprising: a cartridge fitted into the internalperiphery of a shaft hole of the housing; a first lip seal member fittedin a non-bonded state to the cartridge; a case fitted in a non-bondedstate to the first lip seal member; a second lip seal member crimpedonto and held by the case, and a backup ring for supporting the secondlip seal member; and an adapter fitted into the cartridge on a sealingfluid side of the first lip seal member, wherein the adapter is annularin overall shape with a cross-sectional shape that is substantially theshape of the letter “c,” and has an external peripheral flange incontact with an internal peripheral surface of the cartridge and aninternal peripheral flange and web for pressing the first lip sealmember; and the external peripheral flange has a tapered shape thatdecreases in diameter toward the web side, a distal end part of theoutside diameter side describing an acute angle, and being formed to adiameter that is greater than the diameter of the internal peripheralsurface of the cartridge.

In accordance with the first aspect, the adapter can be smoothly fittedinto the internal peripheral surface of the cartridge when fitting iscarried out. Also, when the adapter has been fitted, the adapter is lessliable to dislodge from the cartridge. Therefore, the movement of theseal lip of the first lip seal member can be prevented, sealingperformance can be reliably maintained.

Furthermore, the adapter can be readily fabricated because slightdimensional variability is absorbed by elastic deformation of theexternal peripheral-side flange without the need to fabricate theadapter with rigorous dimensional precision.

The shaft seal device of a second aspect is the shaft seal device of thefirst aspect, and is characterized in that the web of the adaptercomprises an external-periphery-side portion having an orthogonal planarshape orthogonal to the center of the shaft, and a taperedinternal-periphery-side portion that slopes to the sealing fluid side.

In accordance with the second aspect, variation in the inside diameterdimension of the first seal lip member can be suppressed without theinternal peripheral side of the first seal lip member being excessivelycompressed to the atmosphere side by the web of the adapter, even whenthe internal-periphery-side portion of the web is extended inward in theradial direction to reduce the inside diameter dimension of the adapter.The first seal lip member is pressed by the adapter over wide range inthe radial direction, and the movement of the first seal lip member inthe axial direction can therefore be suppressed even when the shaft sealdevice is inserted onto the shaft.

The shaft seal device of a third aspect is the shaft seal device of thefirst or second aspect, and is characterized in that, in the web of theadapter, the ratio of the widths in the radial direction of theexternal-periphery-side portion having an orthogonal planar shape andthe tapered internal-periphery-side portion is set so that the taperedinternal-periphery-side portion is greater.

In accordance with the third aspect, excessive compression of the firstseal lip member can be prevented even in the case that inside diameterdimension of the adapter is reduced in response to the shaft diameterand the width of the web in the radial direction is increased.

The shaft seal device of a fourth aspect is the shaft seal device of thesecond or third aspect, and is characterized in that an interval d inthe radial direction between an internal peripheral surface of theadapter and an upper surface of a seal lip of the first seal lip memberis about 0.1 mm or more and less than 1.3 mm.

In accordance with the fourth aspect, the width of the adapter in theradial direction can be maximally increased without compromising thesealing function of the seal lip, and movement of the first seal lipmember in the axial direction can be suppressed even when the shaft sealdevice is inserted onto the shaft.

Effect of the Invention

The present invention has the following excellent effects.

(1) The adapter is annular in overall shape with a cross-sectional shapethat is substantially the shape of the letter “c,” and has an externalperipheral flange in contact with the internal peripheral surface of thecartridge and an internal peripheral flange and web for pressing thefirst lip seal member. The external peripheral flange has a taperedshape that decreases in diameter toward the web side. A distal end partof the outside diameter side describes an acute angle and is formed to adiameter that is greater than the diameter of the internal peripheralsurface of the cartridge, whereby the adapter can be smoothly fittedwhen the adapter is to be fitted to the internal peripheral surface ofthe cartridge. Also, when the adapter has been fitted, the adapter isless liable to dislodge from the cartridge. Therefore, the movement ofthe seal lip of the first lip seal member can be prevented, and sealingperformance can be reliably maintained.

Furthermore, the adapter can be readily fabricated because slightdimensional variability is absorbed by elastic deformation of theexternal peripheral-side flange without the need to fabricate theadapter with rigorous dimensional precision.

(2) The web of the adapter is composed of an external-periphery-sideportion having an orthogonal planar shape that is orthogonal to thecenter of the shaft, and an internal-periphery-side portion having atapered shape that slopes to the sealing fluid side, whereby variationin the inside diameter dimension of the first seal lip member can besuppressed without the internal peripheral side of the first seal lipmember being excessively compressed to the atmosphere side by the web ofthe adapter, even when the internal-periphery-side portion of the web isextended inward in the radial direction to reduce the inside diameterdimension of the adapter. The first seal lip member is pressed by theadapter over wide range in the radial direction, and the movement of thefirst seal lip member in the axial direction can therefore be suppressedeven when the shaft seal device is inserted onto the shaft.

(3) In the web of the adapter, the ratio of the widths in the radialdirection of the external-periphery-side portion having an orthogonalplanar shape and the tapered internal-periphery-side portion is set sothat the tapered internal-periphery-side portion is greater, wherebyexcessive compression of the first seal lip member can be prevented evenin the case that inside diameter dimension of the adapter is reduced inresponse to the shaft diameter and the width of the web in the radialdirection is increased.

(4) An interval d in the radial direction between an internal peripheralsurface of the adapter and an upper surface of a seal lip of the firstseal lip member is about 0.1 mm or more and less than 1.3 mm, wherebythe width of the adapter in the radial direction can be maximallyincreased without compromising the sealing function of the seal lip, andmovement of the first seal lip member in the axial direction can besuppressed even when the shaft seal device is inserted onto the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front cross-sectional diagram showing the shaft seal deviceaccording to embodiment 1 of the present invention;

FIG. 2 is a diagram for illustrating the adapter of the shaft sealdevice according to embodiment 1 of the present invention, wherein FIG.2( a) is a front cross-sectional view of the adapter, and FIG. 2( b) isa view illustrating the state in which the adapter is press-fitted;

FIG. 3 is a front cross-sectional diagram showing the shaft seal deviceaccording to embodiment 2 of the present invention;

FIG. 4 is a diagram for illustrating the adapter of the shaft sealdevice according to embodiment 2 of the present invention, wherein FIG.4( a) is a front cross-sectional view of the adapter, and FIG. 4( b) isa view illustrating the state in which the adapter is press-fitted;

FIG. 5 is a diagram for illustrating the assembled state of the shaftseal device according to a shaft seal device of prior art and the shaftseal device according to an embodiment of the present invention, whereinFIGS. 5( a) and 5(b) show the shaft seal device of prior art, and FIGS.5( c) and 5(d) show the shaft seal device according to embodiment 2 ofthe present invention; and

FIG. 6 is a front cross-sectional view showing a shaft seal device ofprior art.

BEST MODE FOR CARRYING OUT THE INVENTION

Modes for carrying out the shaft seal device according to the presentinvention are described in detail below with reference to the drawings,but the present invention should not be interpreted as being limitedthereby, and various modifications, changes, and improvements that donot depart from the scope of the present invention can be made on thebasis of the knowledge of those skilled in the art.

[Embodiment]1

FIG. 1 is a front cross-sectional diagram showing the shaft seal device10 according to embodiment 1 of the present invention, and the shaftseal device 10 is configured in the following manner.

The right side of the diagram is the sealing fluid side L and the leftside is the atmosphere side A.

The shaft seal device 10 is mounted on the internal periphery of a shafthole 2 of a housing 1 of a water pump or the like so as to be inslidable close contact with the peripheral surface of a shaft 3, and isprovided with a two-step lip structure having a first seal lip 11 madeof rubber material arranged on the sealing fluid side L, and a secondseal lip 12 made of resin material arranged on the atmosphere side A.

The shaft seal device 10 has six constituent components: a cartridge 13fitted into the internal periphery of the shaft hole 2 of the housing 1;a first seal lip member 14 made of rubber material that is fitted intoand held by the cartridge 13 in a non-bonded state; a case 15 that isfitted into and held by the first seal lip member 14 in a non-bondedstate; a second lip seal member 16 made of resin material that iscrimped to and held in place by the case 15; a backup lip ring 17 thatis similarly crimped to and held in place by the case 15 and that isarranged on the atmosphere side A of the second lip seal member 16 andused for supporting the second lip seal member 16; and an adapter 18that is fitted into the cartridge 13 on the sealing fluid side L of thefirst seal lip member 14 to thereby stop the first seal lip member 14from being dislodged from the cartridge 13.

The cartridge 13 is a pressed article made of metal, e.g., a metalplate, is molded into a ring shape overall, has a cylindrical part 19that is fitted into the internal periphery of the shaft hole 2 of thehousing 1, and is integrally formed with an inward-facing flange 20 thatfaces inward in the radial direction on the atmosphere side A. Anoutward-facing flange 21 that faces outward in the radial direction isintegrally formed on the sealing fluid side L of the cylindrical part19. The inward-facing flange 20 functions as an end wall part with whichthe case 15 makes contact from one of the axial directions when theshaft seal device 10 is assembled, and functions as an end wall partthat sandwiches the case 15 and the first seal lip member 14 against theadapter 18 after assembly. The outward-facing flange 21 has a functionfor determining insertion length by coming into contact with theperipheral edge part of the opening of the shaft hole 2 of the housing 1when the shaft seal device 10 is inserted into the shaft hole 2 of thehousing 1. An external peripheral seal member 4 composed of an elasticcoating for forming a sealing effect with the internal peripheralsurface of the shaft hole 2 is affixed around the entire periphery ofthe external peripheral surface of the cylindrical part 19.

The first seal lip member 14 is composed of a predetermined rubbermaterial (e.g., H-NBR) and has: an overall annular shape; a cylinderpart 22 fitted in a non-bonded state to the internal peripheral surfaceof the cylindrical part 19 of the cartridge 13; a discoid part 23 thatextends from the end part of the sealing fluid side L of the cylinderpart 22 inward in the radial direction; and a seal lip 24 that isintegrally formed from the internal peripheral-side end part of thediscoid part 23 toward the sealing fluid side L. The seal lip 24 is inslidable close contact with the peripheral surface of the shaft 3 at thelip end 24 a thereof, and has a threaded part 25 that creates a pumpingaction during shaft rotation and that is provided to the slidingsurface.

The case 15 is composed of a press-machined article made of, e.g.,stainless steel, is molded into a ring shape overall, is the internalperipheral side of the cylinder part 22 of the first seal lip member 14,and has: a cylindrical part 26 that is fitted between the discoid part23 and the inward-facing flange 20 of the cartridge 13 in a non-bondedstate; has a first flange 27 integrally formed from the end part of thesealing fluid side L of the cylindrical part 26 inward in the radialdirection; and a second flange 28 integrally formed from the end part ofthe atmosphere side A of the cylindrical part 26 inward in the radialdirection. The cylindrical part 26 is in close contact with the cylinderpart 22 of the first seal lip member 14, the first flange 27 is in closecontact with the discoid part 23, and the second flange 28 is in closecontact the inward-facing flange 20 after assembly.

The second lip seal member 16 is composed of, e.g., PTFE, or anotherresin material, is molded into a ring shape overall, and has a discoidpart 29 and a seal lip 30 integrally formed so as to slope from the endpart of the internal periphery of the discoid part 29 to the sealingfluid side L. The seal lip 30 is in slidable close contact with theperipheral surface of the shaft 3 at the lip end 30 a, is arranged onthe atmosphere side of the first seal lip member 14, and therefore formsa secondary seal while the first seal lip member 14 forms a primaryseal.

The backup lip ring 17 is composed of a press-machined article made of,e.g., stainless steel, has a ring shape overall, and has a cylinder part31 and a flange 32 that is integrally formed from the end part of thesealing fluid side L of the cylinder part 31 inward in the radialdirection. The backup lip ring 17 is arranged on the atmosphere side Aof the second lip seal member 16 and supports the second lip seal member16 from the atmosphere side A thereof.

The second lip seal member 16 and the backup lip ring 17 are crimped toand held by the case 15, as described above, and constitute the internalperipheral side of the cylindrical part 26 of the case 15. The discoidpart 29 of the second lip seal member 16 and the flange 32 of the backuplip ring 17 are lined up in the axial direction between the first andsecond flanges 27, 28 and are crimped and secured. After crimping, thesecond lip seal member 16 is pressed into contact with the first flange27 via the discoid part 29.

The adapter 18 is composed of a pressed article made of, e.g., stainlesssteel in similar fashion to the case 15 and the backup lip ring 17, andhas: a ring shape overall with a cross-sectional shape that issubstantially the shape of the letter “c;” an external peripheral-sideflange 33 fitted to the internal peripheral surface of the cylindricalpart 19 of the cartridge 13 on the sealing fluid side L of the cylinderpart 22 of the first seal lip member 14; a web 34 integrally formed fromthe end part of the atmosphere side A of the external peripheral-sideflange 33 inward in the radial direction; and an internalperipheral-side flange 35 that is curved toward the sealing fluid side Land formed from the end part of the internal peripheral side of the web34. The adapter 18 presses the first seal lip member 14 toward theatmosphere side via the web 34, retains the web, and stabilizes theorientation.

FIG. 2 is a diagram for illustrating the adapter 18 of the shaft sealdevice according to embodiment 1 of the present invention, wherein FIG.2( a) is a front cross-sectional view of the adapter 18, and FIG. 2( b)is a view illustrating the state in which the adapter 18 ispress-fitted. The adapter 18 has a ring shape overall with across-sectional shape that is substantially the shape of the letter “c,”as shown in FIG. 2( a), and has an external peripheral-side flange 33 incontact with the internal peripheral surface of the cartridge 13 and aweb 34 and internal peripheral-side flange 35 that press the first seallip member 14. The external peripheral-side flange 33 has a taperedshape that decreases in diameter toward the web side. The externaldiameter-side distal end part 38 describes an acute angle and is formedto a diameter that is greater than the diameter of the internalperipheral surface of the cylindrical part 19 of the cartridge 13.

When the adapter 18 is press-fitted to the internal peripheral surfaceof the cartridge 13, the adapter can be smoothly fitted because theexternal peripheral-side flange 33 has a tapered shape, as shown in FIG.2( b). Since the external diameter-side distal end part 38 describes anacute angle and is formed to a diameter that is greater than thediameter of the internal peripheral surface of the cylindrical part 19of the cartridge 13, the adapter 18 is press-fitted while the externalperipheral-side flange 33 elastically deforms inward in the mannerindicated by the alternate long and two short dashes line. Accordingly,the web 34 also slopes slightly to the atmosphere side A, as indicatedby the alternate long and two short dashes line.

In FIG. 1, the shape of the adapter 18 prior to press-fitting isindicated by a broken line, and the shape of the adapter 18 afterpress-fitting is indicated by the solid line.

After the adapter 18 has been press-fitted, the external diameter-sidedistal end part 38 bites into the internal peripheral surface of thecartridge 13 because the external peripheral-side flange 33 attempts toreturn to its original shape. Therefore, the adapter 18 is unlikely todislodge after having been fitted.

The internal peripheral-side flange 35 doubly functions to improve thestrength of the adapter 18 and to prevent damage to the first seal lipmember 14, and may have a curvilinear shape smoothly curved from theinternal peripheral side of the web 34, e.g., an arcuately curved part.

[Embodiment]2

FIG. 3 is a front cross-sectional diagram showing the shaft seal device10 according to embodiment 2 of the present invention. In the shaft sealdevice 10 according to embodiment 2, the shaft 3 has a smaller diameterthan the shaft 3 of embodiment 1. Therefore, the five constituentcomponents: the first seal lip member 14, the case 15, the second lipseal member 16, the backup lip ring 17, and the adapter 18, aredifferent from embodiment 1 in terms of the shape that corresponds tothe smaller diameter shaft 3. Accordingly, the same reference numeralsare used for the same members that correspond to embodiment 1, andexcept for the points of difference, a detailed description thereof willbe omitted.

In the shaft seal device 10 according to embodiment 2, the insidediameter dimension of the first seal lip member 14, the case 15, thesecond lip seal member 16, and the backup lip ring 17 must be reduced incomparison with embodiment 1, as shown in FIG. 3. Therefore, the widthin the radial direction of the discoid part 23 of the first seal lipmember 14, the first flange 27 of the case 15, the discoid part 29 ofthe second lip seal member 16, and the flange 32 of the backup lip ring17 is formed with greater width in the radial direction.

Accordingly, the adapter 18 is also formed with a reduced insidediameter dimension.

The adapter 18 has a ring shape overall with a cross-sectional shapethat is substantially the shape of the letter “c,” and an externalperipheral-side flange 33 fitted to the internal peripheral surface ofthe cylindrical part 19 of the cartridge 13 on the sealing fluid side Lof the cylinder part 22 of the first seal lip member 14. A web 34 isintegrally formed from the end part of the atmosphere side A of theexternal peripheral-side flange 33 inward in the radial direction, andan internal peripheral-side flange 35 is curved toward the sealing fluidside L and formed from the end part of the internal peripheral side ofthe web 34. The adapter 18 presses the first seal lip member 14 towardthe atmosphere side via the web 34, retains the web, and stabilizes theorientation. The internal peripheral side of the web 34 extends inwardin the radial direction to a point proximate to the intersection mbetween the seal lip 24 and the discoid part 23 of the first seal lipmember 14 so that the function of the web can be sufficientlydemonstrated.

FIG. 4 is a diagram for illustrating the adapter 18 of the shaft sealdevice according to an embodiment of the present invention, wherein FIG.4( a) is a front cross-sectional view of the adapter 18, and FIG. 4( b)is a view illustrating the state in which the adapter 18 ispress-fitted. The adapter 18 has a ring shape overall with across-sectional shape that is substantially the shape of the letter “c,”as shown in FIG. 4( a), and has an external peripheral-side flange 33 incontact with the internal peripheral surface of the cartridge 13 and aweb 34 and internal peripheral-side flange 35 that press the first seallip member 14. The external peripheral-side flange 33 has a taperedshape that decreases in diameter toward the web 34 side. The externaldiameter-side distal end part 38 describes an acute angle and is formedto a diameter that is greater than the diameter of the internalperipheral surface of the cylindrical part 19 of the cartridge 13.

When the adapter 18 is press-fitted into the cartridge 13, the externalperipheral-side flange 33 of the adapter elastically deforms inward inthe radial direction from the state indicated by the solid line to thestate indicated by the alternate long and two short dashes line, asshown in FIG. 4( b), and therefore, the inner side of the web 34 in theradial direction also slopes slightly to the atmosphere side A.Accordingly, when the inside diameter of the adapter 18 issimplistically reduced and the width in the radial direction isincreased, the internal peripheral side of the first seal lip member 14is compressed by a considerable distance to the atmosphere side by theweb 34 of the adapter 18, the inside diameter dimension of the firstseal lip member 14 varies, and seal function is negatively affected.Therefore, the width of the adapter 18 in the radial direction cannot beincreased.

In view of this fact, in embodiment 2, the web 34 of the adapter 18 isformed from an external-periphery-side portion 36 having an orthogonalplanar shape that is orthogonal to the center of the shaft, and ainternal-periphery-side portion 37 that slopes to the sealing fluidside, as shown in FIG. 4( a), whereby the internal peripheral side ofthe web 34 can extend inward in the radial direction to a pointproximate to the intersection m between the seal lip 24 and the discoidpart 23 of the first seal lip member 14. In other words, even when theinternal peripheral side of the web 34 extends inward in the radialdirection, the internal peripheral side of the web 34 is set so as to bein a substantially vertical state even when the web 34 slopes to theatmosphere side A when the adapter 18 is press-fitted into the cartridge13, because the internal-periphery-side portion 37 is formed having atapered shape that slopes to the sealing fluid side. Therefore, it ispossible to prevent the internal peripheral side of the first seal lipmember 14 from being excessively compressed to the atmosphere side andto suppress variation in the inside diameter dimension of the first seallip member 14.

The angle of the taper of the internal-periphery-side portion 37 isdetermined by design, and in the present embodiment, the angle is 4° to8°, and is preferably about 6°.

The ratio of the widths in the radial direction of theexternal-periphery-side portion 36 having an orthogonal planar shape andthe internal-periphery-side portion 37 having a tapered shape ispreferably set so that the tapered internal-periphery-side portion 37 isgreater in the web 34 of the adapter 18. Furthermore, in FIG. 3, aninterval d in the radial direction between an internal periphery of theadapter 18 and an upper surface of a seal lip 24 of the first seal lipmember 14 is preferably about 0.1 mm or more and less than 1.3 mm on oneside.

With the web 34 of the adapter 18 formed in this manner, the internalperipheral side of the first seal lip member 14 is prevented from beingexcessively compressed to the atmosphere side by the web 34 of theadapter 18 and it is possible to suppress variation in the insidediameter dimension of the first seal lip member 14, even when the insidediameter dimension of the adapter 18 is reduced and the width of the web34 in the radial direction is increased. Also, movement of the firstseal lip member 14 in the axial direction can be suppressed even whenthe shaft seal device is inserted onto the shaft 3.

FIGS. 5( c) and 5(d) are diagrams for illustrating the assembled stateof the shaft seal device 10 according to embodiment 2. In FIG. 5( c)showing the state in which the shaft seal device 10 has been assembledon the shaft 3, a large portion of the discoid part 23 of the first seallip member 14 is pressed by the adapter 18. Therefore, the seal lip 24does not move, a state of contact is maintained between the first seallip member 14 and the case 15, and the state is substantially the sameas that prior to assembly. In contrast, in the shaft seal device of theprior art of FIG. 5( a), a gap 69 is formed between the first seal lip63 and the case 64, and it is apparent that the first seal lip 63 hasmoved due to assembly on the shaft 70.

On the other hand, it is apparent that the state in which systempressure is applied to the sealing fluid side L in FIG. 5( d) issubstantially the same state as that of FIG. 5( c). In other words,since the first seal lip member 14 and the case 15 are in a state ofcontact prior to system pressure being applied, the seal lip 24substantially does not move even though the seal lip 24 of the firstseal lip member 14 is pressed against the seal lip 30 of the second lipseal member 16 when system pressure is applied.

As described above, the adapter according to the present invention isreadily fitted and unlikely to dislodge because an externalperipheral-side flange has a tapered shape, an external diameter-sidedistal end part describing an acute angle and having a diameter that isgreater than the diameter of the internal peripheral surface of thecartridge. Also, excessive compression of the first seal lip member isprevented and variation in the inside diameter dimension of the firstseal lip member can be suppressed even when inside diameter dimension ofthe adapter is reduced and the width of the web is increased in theradial direction, because the web is formed from anexternal-periphery-side portion having an orthogonal planar shape thatis orthogonal to the center of the shaft, and a taperedinternal-periphery-side portion that slopes to the sealing fluid side.It is furthermore possible to press a large portion of the first seallip member to the sealing fluid side. Therefore, movement of the firstseal lip member in the axial direction can be suppressed even when theshaft seal device is inserted onto the shaft.

KEY TO THE SYMBOLS

1 housing

2 shaft hole

3 shaft

4 external peripheral seal member

10 shaft seal device

11 first seal lip

12 second seal lip

13 cartridge

14 first seal lip member

15 case

16 second lip seal member

17 backup lip ring

18 adapter

19 cylindrical part

20 inward-facing flange

21 outward-facing flange

22 cylinder part

23 discoid part

24 seal lip

25 threaded part

26 cylindrical part

27 first flange

28 second flange

29 discoid part

30 seal lip

31 cylinder part

32 flange

33 external peripheral-side flange

34 web

35 internal peripheral-side flange

36 external-periphery-side portion

37 internal-periphery-side portion

38 external diameter-side distal end part

L sealing fluid side

A atmosphere side

The invention claimed is:
 1. A shaft seal device for sealing a spacebetween a housing and a rotating shaft, the shaft seal devicecomprising: a cartridge fitted into the internal periphery of a shafthole of said housing; a first lip seal member fitted in a non-bondedstate to said cartridge; a case fitted in a non-bonded state to saidfirst lip seal member; a second lip seal member crimped onto and held bysaid case, and a backup ring for supporting the second lip seal member;and an adapter fitted into said cartridge on a sealing fluid side ofsaid first lip seal member, wherein said adapter is annular in overallshape with a cross-sectional shape that is substantially the shape ofthe letter “c” and has an external peripheral flange in contact with aninternal peripheral surface of said cartridge and an internal peripheralflange and web for pressing said first lip seal member; said externalperipheral flange has a tapered shape that decreases in diameter towardsaid web side, a distal end part of the outside diameter side describingan acute angle, and being formed to a diameter that is greater than thediameter of the internal peripheral surface of said cartridge; and saidweb of said adapter comprises an external-periphery-side portion havingan orthogonal planar shape orthogonal to the center of the shaft, and atapered internal-periphery-side portion that slopes to the sealing fluidside.
 2. The shaft seal device according to claim 1, characterized inthat an interval d in the radial direction between an internalperipheral surface of said adapter and an upper surface of a seal lip ofthe first seal lip member is about 0.1 mm or more and less than 1.3 mm.3. The shaft seal device according to claim 1, characterized in that, insaid web of said adapter, the ratio of the widths in the radialdirection of the external-periphery-side portion having an orthogonalplanar shape and the tapered internal-periphery-side portion is set sothat the tapered internal-periphery-side portion is greater.
 4. Theshaft seal device according to claim 3, characterized in that aninterval d in the radial direction between an internal peripheralsurface of said adapter and an upper surface of a seal lip of the firstseal lip member is about 0.1 mm or more and less than 1.3 mm.